The invention is adapted especially for use in stator assemblies for torque converter transmissions in an automotive vehicle driveline. The invention may be used also in other applications, however, such as torque transfer drives and chain drives that require an overrunning coupling in a torque flow path.
Torque converter transmissions include a stator assembly having a stator hub secured to a stationary sleeve shaft and stator blades situated between a toroidal flow exit section of a hydrokinetic turbine and the toroidal flow entrance section of a hydrokinetic impeller. The blades of the stator change the direction of the tangential component of the toroidal flow velocity vector at the turbine exit section prior to entry of the toroidal flow to the impeller entrance section. This permits multiplication of torque as the hydrokinetic converter delivers engine power to a power input element of multiple ratio gearing in the transmission mechanism.
It is known practice in the automotive transmission art to design the stator assembly of a hydrokinetic torque converter transmission with a stator hub that is adapted to receive an overrunning coupling having an outer race and an inner race, the inner race being splined to a stationary sleeve shaft and the outer race being carried by the bladed section of the stator assembly. The outer race typically would be cammed to provide a plurality of cam surfaces that are engageable by overrunning coupling rollers. The overrunning coupling permits reaction torque delivery from the stator blades to the stationary sleeve shaft when the torque converter is in a torque multiplication mode. The rollers and the cam surfaces with which they interact will permit free-wheeling motion of the bladed section of the converter when the torque converter is in a coupling mode.
The outer race of a conventional overrunning stator coupling is keyed or splined in a central opening in the stator hub. It is held in place by snap rings located in snap ring grooves machined in the stator hub.
My prior U.S. Pat. No. 5,597,057, which is owned by the assignee of the present invention, and which is hereby incorporated by reference in its entirety, provides an improved overrunning coupling assembly having an annular coupling pocket plate with strut pockets disposed therein and a notch plate disposed in face-to-face relationship with the pocket plate. The notch plate includes notch recesses at angularly spaced positions about the axis and disposed in juxtaposed relationship with respect to the strut pockets. Torque-transmitting struts are positioned in the strut pockets and spring-biased for engagement with the notch recesses.
Further improvements in overrunning coupling designs are desirable, particularly those improvements which reduce manufacturing costs and eliminate wear issues. For example, one potential problem associated with the above-referenced overrunning coupling design is that a certain amount of noise may be generated by the struts "slapping" or rattling against the notch recesses of the notch plate. Also, wear of the strut on top and edge surfaces during overrun may be a concern. It is also desirable to eliminate the need for constant and controlled lubrication.